On Mon, Feb 08, 2016 at 02:53:57PM +0000, Gert Grammel wrote:
> 
> 
> >This is not what is being proposed. We always had
> >
> >[candidate] -> [running] -> operational state
> >
> >(and I mark configuration data stores in []). Both [candidate] and
> >[running] have the same configuration data model. Now we are asked
> >to expose that [running] may not be applied synchronously and hence
> >
> >[candidate] -> [running] -> [applied] -> derived state
> >
> >seems to make sense.

Why would that be the case? If I configure an interface that is not
currently present today in running this is just find and running is
not expected to change arbitrarily.
 
> The mapping of what is called intended-config onto data stores would
> deserve more detailed discussion. It seems the authors of this draft had
> in mind to associate intended-cfg with the [running] datastore. With that
> mapping, a failure in applying [running] to [applied] will update the
> [running] datastore to reflect which part is effectively applied. So a
> fair representation of that case would be:
> [candidate] -> [running] <--> [applied] -> derived state

What is 'this draft'? I thought the whole point of having an applied
config is to be able to see the difference between intended (oops
running) and applied. I am confused now.
 
> In the context of intended configuration however that doesn¹t make sense
> to me. A failure in applying intended configuration doesn¹t change the
> intention and the delta between intended and applied-config is the key
> value. A server that would "clean-up² intended-cfg in presence of a
> failure to apply would look picture perfect instead of exposing the
> problem clearly. Hence the sequence should more look like:
> [candidate] -> [intended] ‹> [running==applied] -> derived state
> 
> Whatever we choose, I believe we need to spell out what¹s the data in a
> failure case. It¹s probably a bit late to update the requirements draft,
> but we can probably find a suitable place.

There is apparently much less agreement on what the problem is, what
the terms mean, and how they related to existing technology than I
thought.

/js

-- 
Juergen Schoenwaelder           Jacobs University Bremen gGmbH
Phone: +49 421 200 3587         Campus Ring 1 | 28759 Bremen | Germany
Fax:   +49 421 200 3103         <http://www.jacobs-university.de/>

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